My experience with D2X and stitching:
I´ve been taken panoramas with a D100 for several years, and with a D2X for half and a year.
Usually I first take a photo with a wide-angle lens to check for the metering in what is something like an aproach to the final photo.
I use manfrotto´s pano head, to keep the camera rotating on the lens nodal point, fix shutter and aperture as previously metered, and fix white balance.
The lens is always above 50mm. Photogramas have to be overlaped between 20 to 40 % for better results. (Depending on the lens, the subject, etc)
I stitch photograms with Panavue Image Assembler, setting manual joining points, and keeping layers for final retouching on Photoshop.
This method is very "time - consuming", sometimes getting good results, and sometimes not.
I also have used the D2X on a Cambo Ultima 4x5 Camera. My idea was to get the images I needed with more resolution, without investing on a MF digital back.
So I got the 35mm accessory for the Cambo, as well as the 23 front standard, to have the Nikon working right on axis.
You can take several shots (usually 4 to 5) shifting the cambo´s back with the nikon mounted with the vertical adaptor.
This allows for an image between 12x3 to 12x4 megapixels, which can be quickly and perfectly stitched on Photoshop, usually without any king of warping. (The Cambo keeps the focal plane for the shots as you shift the back of the camera laterally). (You need to set manual aperture / shutter/ white balance...)
The main problem I have encountered using this method is the poor quality of the lenses. (And so the photographs)
There´s a highly noticeable difference between shots taken with good nikon optics and the ones used on the Cambo. (I use several Schneider Digitar lenses, and the 28mm is specially dissapointing.)
Also, depending on how much you swing or tilt the camera, you are not able to shift the back the full 25mm left / right
Because of the way the sensor is kept inside the body, and its size, I personally cannot recommend to use the Nikon for shooting this way. (Another drawback is that there are just a few lenses to choose which can focus on the sensor area.)
Same problems should apply on shooting on a Sinar P. (Also the camera is not kept on axis and focus has to be checked after any swing - tilt movement)
The Vcc option at horseman keeps the MoreResolution/LessLensQuality vs LessResolution/HighLensQuality subject, and also the disadvantage(?) of being limited to lenses over 80mm.
As it seems you have all the "ingredients" to check the results on your Sinar, you can try and see the results, and share them on the web.
Hope my post helps,